1. Field
The present invention relates to reducing EMI emissions, and more particularly, to circuitry for encoding signals so as to reduce EMI emissions.
2. Background Information
It is well-known that regular bit patterns or binary digital signal patterns in electronic devices, such as computers or personal computers, increase the levels of electromagnetic (EMI) emissions. One example of this phenomenon is the EMI emissions produced by clocks employed in digital circuitry, such as may be employed in a personal computer, for example. As a method of ensuring consistency of EMI measurement for video signals/interfaces, the Federal Communications Commission (FCC) has defined the use of a scrolling “H” pattern when doing compliance testing for EMI emissions. Unfortunately, the use of a scrolling “H” pattern generally increases the EMI emission levels and, furthermore, digital video interface EMI emission levels are more noticeably affected by this scrolling “H” pattern than, for example, analog video interfaces. For example, up to 24 individual traces may be employed in such a digital video interface, where 24 bits indicating color, for example, are employed. Of course, this problem is not limited to a 24 bit interface. A need, therefore, exists for a method or technique of reducing EMI emissions, particularly in digital video interfaces, such as when the signals are being transmitted across a signal bus or interconnect, or between two components, or between a component and display, for example.